Vacuum pump



O. SEITZ VACUUM PUMP July 1, 1930.

Fi1ed Aug. 21 1926 V ,1 wezaaa n 05 62/56622'61 W WW Wessex 10 usage. i

3 Patented July 1, 1930 H N TED}.STATES PA T'ET FF HC osKAR sErrz, on jIBADEN; swi'rzER Aiv-n, 'nssrenon TO AKTIENGESELLSCHAFT BROWN BOVERI -&om. on BADEN," SWITZEBLAND,- A CORPORATION on SWITZERLAND Application filerl Angust glpml Serial No.

This invention relates to high vacuum 1 um s of the t )e o aeratin, 1 with mercur vapor on the ejector or dittusionprinciples."

It has particular reference to the construction of a-ll n'1etal pumpswhich are qualified] and which,"accordingly must be of sturdy.

construction to Withstand rough. or trying The general objectof the inventionyis the possess the requisite strength andhave increased operating eiie'ctiv'eness and" efliciency' '1 Another oblect is the provision of a conupon an understandingof the invention or its 7 employment inpra-ctlce.

In the drawing,' ""v .1 V Fig. leis a sectionalelevatiomtaken 011a diameteigo'f a single the invention; and

Fig. 2 is a similar two stage pump.

stage pump embodying pumps in which a gasls moved by an up-v produced in a connected vessel; v of the inventionwill best be understoodby "in contact with the outer surfa'ceof the cas-,

i ing 10. The casing 10 is provided adjacent its lower end with an inlet connection 12 which is arranged to be placed 1n communication. with the vessel to be evacuated. Y At its upper portion the chamber within the casing i 10 has an outlet through a connection 1t;

which is arranged to be placed in communicaprovision of a pump construction which will tr igqbi e endedvant e will be pointed outer indicated herelnafter p or willbeapparent to one sk lled' n the art sectional elevation of a The invention is concernedIwithj metallic reference immediately; to the illustrative tion with the receiver of a preliminaryiva'cu um pump which is effective to draw gases mama inGermany September 21, 1925.

from said chamber. At its lowerend below the connection 12, the casing 10 is in communicationwit'h a generator 15, which contains a body of'mercury 16, to'be vaporized by heat from the heating element 17. Within the casing 10, and aboutthe"connnunicating passage to the generator 15, is disposed a Venturi tube member 18, seating in the seal '19, and axially" within this member projects I a flow-directing member 20, the "wall "of which', in cooperation with the tube 18, provides an'annular nozzle 21. The member 20 may be'supported in the tube 18by thin fins" 22, so arranged as to present-minimum: obstruction to flow of vapor through the tube 18. Atitsupper end, the member 20is supported by a spring 24 which accommodates longitudinal "expansion of said member un; der heat; The water jacket is provided with an inlet 25 and outlet 26. Theiwall of the member 20 diverges orfiaires' toward 'thetop', approaching the. wall of the casing 10, and

affording a"restrictechpassagebetween the two'at thelevel 27'. M I T In operation, the air inlet connection 12 being placed in communication with theves- I sel to be evacuated, andthe air'outlet connection l'tbeing c onnected to a'prel'iminary vac:- uum pump, the mercury, 18' iswapori zedfby the heater 17; producingfa pressure' inthe generator, from which the "vaporpasses through the nozzle member j;18, emerging from .the'nozzle21 at high velocity; By this the inlet connection 12 and propelled toward the-top of the pump casingybecomingdirf fused'meanwhile in the mercury vapor. I The action air is drawn into tfhe-casing10 throngh wall of the membenQO directszthevapor and air. into close association with the cool wall of the casing lO wheleonthe mercury is con dented. The efiect is to propel the air 1 to the upper portion of the i'pu mp casing, whence: it is withdrawn by the preliminary "In the embodimentillustrated-in Fig. 2,

a concentric second stage nozzle member 28,

generator 15 and; sustained the fins 29.

vacuum pump through theoutletfconnection the nozzle member 18 is supplemented with the pump chamber and-has its outlet end Thissecond stage nozzle extends up into operatin with the flow-directing member 20' to provi e a second annular nozzle 30 at an elevation above the upper end of the nozzle member 18. In this construction, the operation is the same as in the one previously described, excepting that the action of the vapor discharged from the nozzle member 18 is supplemented, at higher stage, by the jet from the nozzle 30, and the outer wall of the member 28, which diverges above the nozzle member 18 toward the pump casing 10, functions as a flow-directing member for guiding the vapor and air in Contact with the cooling surface. a It will be observedthat the second nozzle Imembcr 28 is supplied with vapor fronr the generator independently of the nozzle member 18. It is to be understood that provision is made for the return of condensed'mercury from the pump chamber to the generator in a well known manner.

The advantages attained by a pump embo'dying the invention include, in addition to gli capacity for han-' strong construction, a hi dling air, whereby the connected vessel may be rapidly evacuated and a high vacuum produced. 7

What I claim is; r I I I 1. Ina vacuum pump, the combination of a pump casing having an air inlet and an air outlet, a generator, a nozzle tube leading into the pump, casing from thejgenerator and terminating between. the air inlet and outlet,

and a flow-directing member extending within the nozzle tubeand diverging toward the casing Wall.

2., In a vacuum pump, the combination of a pump casing, a generator, a nozzle tube extending into the casing and conimunicating with' 'thegenerator, a flow-directing member extending into the nozzle tube anddiverging toward the casing wall, andmeans for oooling the casing wall.

3. vIn a vacuum pump, the combination of a erator, means disposed in said casingand pro- 7 viding a nozzle for receiving the vapor from said generator, and yieldable' means associated with said nozzle means and providing a support therefor while permitting of conditions of unequal expansion and contraction between the same and said casin '8. In a vacuum pump, a casing, a vapor generator, a tube disposed in said casing and receivingvapor from said. generator, and a member having one end thereof disposed in said tube to provide therewith a nozzle, and

spring means providing ,a support for the other end of said member while permitting of conditions of unequal expansion and contrac-' tion between the same and said casin 9. .In a vacuum pump, a casing, a vapor generator, means disposed in said casing pro- 'viding, a nozzle for directing the vapor formed in said generator, a flow-directing member extendingnto said nozzle and having diverging sides to provide an annular passage-Way with said casing, and means for yieldingly mounting said flow-directing member Within said casing.

In testimony whereof I have hereunto subscribed my name this 5 day of August, A. D. 1926, at Zurich, Switzerland.

OSKAR snirzi pump casing, a generator, a nozzle tube supplied from the generator and discharging in V the pumpcasing, and a, member having one end'thereofextendinginto the discharge end of-saidtubei-and cooperating with the latter to form a nozzle.

In a vacuum pump, the combination 0 I a pump casing, a generator, a nozzle tube su y,

r plied from the generator and discharging in the casing,.and a flow-directing member havingone end thereof extending into the discharge, end of said tube and cooperating therewith to form an ejector nozzle, the other end of said member cooperating with the cas;

ing to form a contracting condensing throat.

5. In a vacuum pump, the combinationof a pumpcasing, a generator, a nozzle tube sup plied from the generator and discharging in P the casing, and aclosed flowedirecting mem; 

